1. Field of the Invention
This invention relates to an endoscope adapted to inspect an object in which either pole of a battery is earthed.
2. Related Art Statement
Recently, industrial endoscopes are extensively utilized to observe and inspect flaws and corrosions within pipings of boilers, gas turbine engines and chemical plants and bodies of automobile engines.
Now, such industrial endoscope has, for example, an elongate insertable section, an operating section provided at the rear end of this insertable section and a light guide cable extended from this operating section and is to be connected to a light source apparatus through a connector provided at the rear end of this light guide cable.
The above mentioned insertable section is formed, for example, of a rigid tip part, a curvable part and a flexible part in the order from the tip side. The members forming the above mentioned insertable section and light guide cable are mostly of a metal and metal parts are often exposed.
A light source apparatus to which this industrial endoscope is connected is earthed. Therefore, as in an automobile or the like, in case one pole of a battery is earthed to the chassis and various electric articles are connected to the other pole of the battery, when such exposed metallic part as of the above mentioned insertable section touches the pole of the battery on the side to which the electric article is connected, an electric current will flow within the endoscope through the metal parts of the insertable section and light guide cable, will destroy an endoscope or such external apparatus as a light source apparatus forming endoscope apparatus, will hurt a car body with a spark, will destroy an electric article and will be further likely to give an electric shock to the operator and observer.
In order to cope with it, in the publication of Japanese Utility Model Application Laid Open No. 162186 1979 is disclosed an endoscope of a structure wherein a jointing member jointing a hardware part tip part of an endoscope tip part and curvable tube part curvable part or a jointing member jointing a curvable tube part and flexible tube part soft part is coated on the outer surface with such insulating layer as of a rubber lining to develop a water leakage preventing function and outer coating insulating function.
However, in the technique shown in the above mentioned publication, in order to insulate the interior of the endoscope so that no electric current may flow, it is a prerequisite that the hardware part of the endoscope tip part and the curvable tube part should be insulatively coated on the outer periphery. That is to say, in case these are not insulatively coated, when they touch the pole of the battery, an electric current will be likely to flow through the insulatively coated jointing member or the metal part inside it.
Now, with the industrial endoscope to be used to inspect or repair an automobile engine or body, as different from the medical endoscope to be used to inspect such object as a human body, an object in which many metal parts are used is inspected and therefore a special consideration for keeping a durability on the outer periphery of the industrial endoscope is necessary. Particularly, in the endoscope tip part and curvable tube part, it may be advantageous to leave the metal as it is on the outer periphery or it may be necessary to secure the durability by coating the metal blade net tube.
Therefore, in the technique shown in the above mentioned publication, it is necessary that the hardware part of the endoscope tip part and curvable part should be insulatively coated on the outer periphery with such material as will remain durable enough even in an environment of many metals. However, such material is generally expensive or often will not be able to be kept durable enough in case it is proper in the price.